Mask pattern correction device, method of correcting mask pattern, light exposure correction device, and method of correcting light exposure

ABSTRACT

In view of realizing a lithographic process which makes it possible to estimate and correct flare with an extremely high accuracy, and causes only an extremely small dimensional variation in width, over the entire portion not only of a single shot region, but also of a single chip region, a mask pattern correction device of the present invention has a numerical aperture calculation unit calculating, for every single shot region, flare energy for a mask pattern corresponding to a transferred pattern, based on an exposure layout of a plurality of shot regions, or more specifically, while considering flare from a plurality of shot regions located around every single shot region.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromthe prior Japanese Patent Application No. 2004-216386, filed on Jul. 23,2004, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a device and method for correcting maskpattern which can correct flare generated in lithographic process, oneof a process step in fabrication of semiconductor devices, and also to adevice and method for correcting light exposure.

2. Description of the Related Art

Recent pattern formation of semiconductor devices adopts projectionexposure apparatuses based on dioptric system or cata-dioptric system.In this sort of projection exposure apparatus, light ascribable to someoptical routes not intended on the design basis, tends to generate dueto reflection and scattering on the surface or inside of lenses in thelighting optical system, photomask, projection lens and so forth, or dueto non-uniformity in refractive index of lens materials. The light isgenerally referred to as “flare”, and is causative of variation in apattern to be transferred or in line width.

FIG. 25 is a drawing schematically showing a mode of flare generation.

In a unit shot region 121 for a single time of light exposure, atransferred pattern formed by light exposure through a mask pattern on aphotomask is irradiated also by flare of the exposure light, which hascome through arbitrary regions B, C away from point A. It is known thatdistance over which the flare can affect reaches as long as severalmillimeters on the basis of distance transferred on a wafer, a targetobject for the pattern transfer. A flare affective to as far as severalmillimeters is referred to as “long-range flare”, a flare of severalmicrometer affective to as far as several tens of micrometers isreferred to as “midrange flare”, and a flare affective to as far asseveral micrometers or less is referred to as “short-range” flare.

In recent years, as typically described in Patent Document 1, there isproposed a technique by which the midrange and short-range flares (localflares) are estimated by using a test pattern composed of a line patternand an annular pattern surrounding thereof, and width of the transferredpattern is corrected based on the estimation.

[Patent Document 1] Japanese Patent Application Laid-Open No.2004-126486

The above-described conventional technique could certainly estimate thelocal flares, which have never been even noticed as a problem to areasonable degree, with a high accuracy, but it has been found that themethod was suffering from difference in the correction accuracy locallyin a single shot region, and could not be said as having reached asatisfactory accuracy yet. This applies not only the midrange andshort-range flares, but also to the long-range flare, and this createsthe present situation in need of development of a dimensional correctiontechnique with a higher accuracy.

The present invention is conceived after considering the above-describedsubjects, and an objects thereof is to provide a device and method forcorrecting a mask pattern, and a device and method for correcting lightexposure, all of which make it possible to estimate and correct flarewith an extremely high accuracy, over the entire portion not only of asingle shot region, but also of a single chip region, to thereby realizea lithographic process causative of only an extremely small dimensionalvariation in line width, and further to thereby realize highly-reliablesemiconductor devices.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, there is provided amask pattern correction device used in pattern transfer, onto a targetobject for pattern transfer, of a mask pattern of a photomask underlight exposure repeated multiple number of times to thereby form atransferred pattern, comprising a numerical aperture calculation unitcalculating, for every single target region, a numerical aperture of themask pattern corresponding to the transferred pattern, based on a layoutof a plurality of the target regions; and a dimension calculation unitcalculating a dimension of the mask pattern necessary for obtaining thetransferred pattern of a predetermined dimension, using the numericalaperture calculated in the above.

According to another aspect of the present invention, there is provideda light exposure correction device used in pattern transfer, onto atarget object for pattern transfer, of a mask pattern of a photomaskunder light exposure repeated multiple number of times to thereby form atransferred pattern, comprising a numerical aperture calculation unitcalculating, for every single target region, a numerical aperture of themask pattern corresponding to the transferred pattern, based on a layoutof a plurality of the target regions; an irradiation energy distributioncalculation unit calculating an irradiation energy distribution of theexposure light in the target region necessary for obtaining thetransferred pattern of a predetermined dimension, using the numericalaperture calculated in the above; and an irradiation energy distributionadjustment unit adjusting the irradiation energy distribution of theexposure light in the target region, based on the irradiation energydistribution calculated in the above.

According to still another aspect of the present invention, there isprovided a light exposure correction device used in pattern transfer,onto a target object for pattern transfer, of a mask pattern of aphotomask under light exposure repeated multiple number of times tothereby form a transferred pattern, comprising a flare energymeasurement unit measuring flare energy generated, when a unit shotregion corresponding to a single time of light exposure is irradiated bythe exposure light, around the unit shot region ascribable to theexposure light; an irradiation energy distribution calculation unitcalculating an irradiation energy distribution of the exposure light inthe unit shot region necessary for obtaining the transferred pattern ofa predetermined dimension, based on the flare energy measured in theabove; and an irradiation energy distribution adjustment unit adjustingthe irradiation energy distribution of the exposure light in the unitshot region, based on the irradiation energy distribution calculated inthe above.

According to still another aspect of the present invention, there isprovided a method of correcting a mask pattern used in pattern transfer,onto a target object for pattern transfer, of a mask pattern of aphotomask under light exposure repeated multiple number of times tothereby form a transferred pattern, comprising the steps of calculating,for every single target region, a numerical aperture of the mask patterncorresponding to the transferred pattern, based on a layout of aplurality of the target regions; and calculating a dimension of the maskpattern necessary for obtaining the transferred pattern of apredetermined dimension, using the numerical aperture calculated in theabove.

According to still another aspect of the present invention, there isprovided a method of correcting light exposure used in pattern transfer,onto a target object for pattern transfer, of a mask pattern of aphotomask under light exposure repeated multiple number of times tothereby form a transferred pattern, comprising the steps of calculating,for every single target region, a numerical aperture of the mask patterncorresponding to the transferred pattern, based on a layout of aplurality of the target regions; calculating an irradiation energydistribution of the exposure light in the target region necessary forobtaining the transferred pattern of a predetermined dimension, usingthe numerical aperture calculated in the above; and adjusting theirradiation energy distribution of the exposure light in the targetregion, based on the irradiation energy distribution calculated in theabove.

According to still another aspect of the present invention, there isprovided a method of correcting light exposure used in pattern transfer,onto a target object for pattern transfer, of a mask pattern of aphotomask under light exposure repeated multiple number of times tothereby form a transferred pattern, comprising the steps of measuringflare energy generated, when a unit shot region corresponding to asingle time of light exposure is irradiated by the exposure light,around the unit shot region ascribable to the exposure light;calculating an irradiation energy distribution of the exposure light inthe unit shot region necessary for obtaining the transferred pattern ofa predetermined dimension, based on the flare energy measured in theabove; and adjusting the irradiation energy distribution of the exposurelight in the unit shot region, based on the irradiation energydistribution calculated in the above.

According to the present invention, it is made possible to estimate andcorrect flare with an extremely high accuracy, over the entire portionnot only of a single shot region, but also of a single chip region, tothereby realize a lithographic process causative of only an extremelysmall dimensional variation in line width, and further to therebyrealize highly-reliable semiconductor devices.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a schematic configuration of a maskpattern data correction device of a first embodiment;

FIG. 2 is a flow chart step-wisely showing a correction method using thedata correction device of the first embodiment;

FIGS. 3A to 3C are schematic drawings of a photomask-for-testing usedfor quantifying flare intensity distribution;

FIG. 4 is a characteristic chart plotting difference values againstvalues of the inner diameter of the individual annular patterns;

FIG. 5 is a characteristic chart showing relations between distance froma line pattern to the individual annular patterns and measured linewidth;

FIG. 6 is a characteristic chart showing a fitted result of the resultsshown in FIG. 5 through integration using equation (1);

FIG. 7A shows a schematic drawing of a photomask-for-testing having ameasurement pattern and a dummy pattern arranged therearound, and FIG.7B shows an enlarged view of the measurement pattern 23;

FIG. 8 is a characteristic chart showing a relation between dimensionalvariation of a test pattern and effective numerical aperture undervaried dimension of the dummy pattern;

FIG. 9 is a schematic drawing showing a design data in a single shotregion of a photomask;

FIG. 10 is a schematic drawing showing an exposure layout of a pluralityof shot regions;

FIG. 11 is a schematic drawing showing a plurality of (three, in theillustrated example) shot regions located around a target shot region;

FIG. 12 is a block diagram showing a schematic configuration of a maskpattern data correction device according to modified example 1 of thefirst embodiment;

FIG. 13 is a flow chart step-wisely showing a correction method usingthe data correction device according to modified example 1 of the firstembodiment;

FIG. 14 is a schematic drawing of a photomask having a mask pattern anddummy pattern arranged therearound so as to adjust the numericalaperture;

FIG. 15A schematically shows a single shot region of an actual device,and FIG. 15B shows an enlarged view of a single chip region;

FIG. 16 is a block diagram showing a schematic configuration of a maskpattern data correction device of a second embodiment;

FIG. 17 is a flow chart step-wisely showing a correction method usingthe data correction device of the second embodiment;

FIG. 18 is a block diagram showing a schematic configuration of a maskpattern data correction device according to a modified example of thesecond embodiment;

FIG. 19 is a flow chart step-wisely showing a correction method usingthe data correction device according to the modified example of thesecond embodiment;

FIG. 20 is a schematic drawing showing a general light exposureapparatus;

FIG. 21 is a block diagram showing a schematic configuration of a maskpattern data correction device according to a third embodiment;

FIG. 22 is a flow chart step-wisely showing a correction method usingthe data correction device of the third embodiment;

FIG. 23A and FIG. 23B are a schematic drawing and a characteristicchart, respectively, showing measurement of flare irradiated outside atarget shot region;

FIG. 24 is a schematic drawing showing an internal configuration of apersonal user terminal device; and

FIG. 25 is a drawing schematically showing a mode of flare generation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Basic Concept of thePresent Invention

The conventional technique was merely such as estimating a local flarewhile placing a focus only on a single shot region. The practical lightexposure is, however, carried out by light exposure, repeated multiplenumber of times, of a resist layer on the surface of a wafer, so thatany one shot region is inevitably affected mainly by neighboring shotregions adjacent thereto. Because accuracy of correction was found todegrade in particular in the peripheral portion of a shot region, thepresent inventors conceived an idea of estimating flare in a single shotregion while considering also flare from a plurality of shot regionslocated around the target shot region.

The present invention classifies targets for the measurement intomiddle(short)-range flare and long-range flare, and proposes aconfiguration adapted to each of the flares. A configuration adapted tothe former uses a mode of correcting design data of a photomask pattern,and a configuration adapted to the latter uses a mode of adjusting theirradiation energy distribution in the light exposure.

In a specific configuration of a mask pattern data correction adapted tothe middle(short)-range flare, estimation of flare in a single shotregion is made while taking a layout of a plurality of shot regions intoconsideration. In this case, a numerical aperture of a mask patterncorresponding to the transferred pattern is calculated while consideringinfluence of flare from other shot regions other than the target shotregion for the calculation, in other words, mask pattern data of othershot regions. This makes it possible to estimate an effective numericalaperture, or flare energy, also for the peripheral portion in the targetshot region with a high accuracy similarly to that obtainable for thecenter portion. Dimension of the mask pattern necessary for obtainingthe transferred pattern of a predetermined dimension is then calculated,using the numerical aperture calculated in the above. This is successfulin realizing a lithographic process causing only an extremely smalldimensional variation in width over the entire portion of the targetshot region.

On the other hand, the long-range flare exerts its influence over arange as long as several millimeters, and shows a moderate variation inthe intensity distribution thereof rather than in a local manner. It istherefore made possible to correct dimension of the transferred patternby adjusting the exposure energy distribution in the target shot region.

In a specific configuration of correction of light exposure according tothe present invention, similarly to as described in the above,estimation of flare in a single shot region is made while taking alayout of a plurality of shot regions into consideration, and anumerical aperture of a mask pattern corresponding to the transferredpattern is calculated while considering influence of flare from othershot regions other than the target shot region for the calculation, inother words, mask pattern data of other shot regions. Usingthus-obtained numerical aperture, an irradiation energy distribution ofthe exposure light in the target shot region, in the reflection ofinfluence of the long-range flare, is then calculated. Because thelong-range flare shows a moderate variation in the intensitydistribution as described in the above, and is therefore adjustable by alight exposure apparatus, the irradiation energy distribution of theexposure light in the target shot region is adjusted based onthus-calculated irradiation energy distribution, as it were, so as toproduce an inverted distribution. This is successful in realizing alithographic process causing only an extremely small dimensionalvariation in width over the entire portion of the target shot region.

In both of the mask pattern data correction and the light exposurecorrection described in the above, it is also allowable herein tocorrect a design value of the numerical aperture for the target shotregion, using an average numerical aperture ascribable to a plurality ofshot regions, in place of using the mask pattern data for other shotregions other than the target shot region for the calculation. This issuccessful in more readily realizing a lithographic process causing onlyan extremely small dimensional variation in width over the entireportion of the target shot region.

Although the above description dealt with the case where only a singleshot region was used as a target region for the calculation, the targetregion may also be a chip region, or both of the shot region and chipregion.

In an exemplary case where the chip region is used as a target regionfor the calculation, adoptable configurations include such asconsidering influences of the flare from other chip regions other thanthe target chip region for the calculation, and such as correcting adesign value of the numerical aperture for the target chip region usingan average numerical aperture ascribable to a plurality of chip regions,similarly to as described in the above. This is successful in realizinga lithographic process causing only an extremely small dimensionalvariation in width over the entire portion of the chip region.

In another specific configuration of the correction of light exposureaccording to the present invention, flare energy generated around theunit exposure region ascribable to the exposure light when the exposurelight is irradiated on a single shot region is measured, and based onthus-measured flare energy, an irradiation energy distribution in thetarget shot region is adjusted typically taking a layout of a pluralityof shot regions into consideration. This is successful in realizing alithographic process causing only an extremely small dimensionalvariation in width over the entire portion of the target shot region.

Specific Embodiments Applied with the Present Invention

The following paragraphs will describe specific embodiments applied withthe present embodiments, referring to the attached drawings.

First Embodiment

Mask pattern data correction adapted to middle(short)-range flare willbe explained in this embodiment.

FIG. 1 is a block diagram showing a schematic configuration of a maskpattern data correction device of a first embodiment.

The data correction device is configured as having a point imageintensity distribution calculation unit 1 calculating flare intensitydistribution (point image intensity distribution) based on a result ofdimensional measurement of a test pattern using a predeterminedphotomask-for-testing; a flare energy-dimensional variation calculationunit 2 calculating a relation between flare energy (effective numericalaperture) and dimensional variation using a dummy photomask adjusted inthe numerical aperture; a flare energy-dimensional correction amountcalculation unit 3 calculating a relation between flare energy anddimensional correction amount; a numerical aperture calculation unit 4calculating, for every single shot region, flare energy for a maskpattern corresponding to a transferred pattern, based on an exposurelayout of a plurality of shot regions, or more specifically, whileconsidering flare from a plurality of shot regions located around everysingle shot region; and a dimension calculation unit 5 calculating adimension of the mask pattern necessary for obtaining the transferredpattern of a predetermined dimension, using the flare energy calculatedin the above.

FIG. 2 is a flow chart step-wisely showing a correction method using theabove-described data correction device.

The data correction method of the present embodiment comprises fivesteps described below:

(1) calculation of flare intensity distribution (point image intensitydistribution) (step S1);

(2) determination of a function expressing relation between flare energy(effective numerical aperture) and dimensional variation (step S2);

(3) determination of a function expressing relation between flare energyand dimensional correction amount (step S3);

(4) calculation of flare energy of the individual mask patterns (stepS4); and

(5) calculation of dimensional correction of the individual maskpatterns (step S5).

The following paragraphs will detail the individual steps.

(1) Step S1

First, a flare intensity distribution of the light at a single point isdetermined.

FIGS. 3A to 3C are schematic drawings of a photomask-for-testing usedfor quantifying the flare intensity distribution, and FIG. 4 is acharacteristic chart showing results of measurement of line widthobtained after projection exposure through the photomask-for-testingshown in FIGS. 3A to 3C. FIG. 3A expresses a photomask-for-testing 11A,FIG. 3B expresses a photomask-for-testing 11B, and FIG. 3C expresses aphotomask-for-testing 11C, respectively.

The photomasks-for-testing 11A, 11B, 11C, has test patterns A to C, . .. , respectively in this order, and each of these test patterns has abasic configuration in which a line pattern 21 and an annular pattern 22surrounding therearound and forming an annular light transmissive regionare combined.

The test pattern A of the photomask-for-testing 11A is composed only ofa line pattern 21 never affected by flare, ensuring completeinterception of light within a 100-μm radius around the line pattern 21.The test pattern B of the photomask-for-testing 11B is composed of aline pattern 21 and an annular pattern 22 arranged therearound so as toform a light transmissive region having an inner diameter of 4.14 μm andan outer diameter of 6.89 μm, ensuring that no pattern other than theannular pattern 21 is formed within an area away, by a distance in needof considering influence by the local flare, from the line pattern 21.The test pattern C of the photomask-for-testing 11C is composed of aline pattern 21 and an annular pattern 22 arranged therearound so as toform a light transmissive region having an inner diameter of 6.89 μm andan outer diameter of 9.65 μm, ensuring that no pattern other than theannular pattern 21 is formed within an area away, by a distance in needof considering influence by the local flare, from the line pattern 21.As described in the above, the individual annular patterns 22 areincreased in the inner diameter of the annulus ring from 4.14 to 48.25μm in increments of 2.76 μm, while keeping the width of the annulus ringconstant at 2.76 μm, so that the inner diameter of the one equals to theouter diameter of the next.

In step S1, first, a photoresist is irradiated through the test patternsA to C, . . . of the photomasks-for-testing 11A to 11C, . . . ,developed, and then subjected to measurement of width of the resultantline patterns 21.

Next, a measured value of the line width of the line pattern 21 in thetest pattern A is compared with measured values of the line width of theindividual line patterns 21 in the test patterns B, C . . . , that is,the difference in the line width respectively between test pattern A andtest patterns B, C, . . . are calculated. The difference values expressvariation in the line width ascribable to the local flare, wherein thesmaller the value becomes, the smaller the local flare with respect tothe line pattern 21 becomes, and the larger the value becomes, thelarger the local flare with respect to the line pattern 21 becomes.

Influence of the local flare through the individual annular patterns 22of the test patterns B, C, . . . , that is, the individual differencevalues with that of the test pattern A, are quantified based on distancebetween the center portion of the line pattern 21 and the annularpattern 22, or more specifically, in terms of the values of the innerdiameter of the individual annular patterns 22.

FIG. 4 shows the difference values plotted against values of the innerdiameter of the individual annular patterns 22, and FIG. 5 showsrelations between distance from the line pattern 21 to the individualannular patterns 22 and measured values of the line width.

It is found that influence of the local flare becomes large for an innerdiameter of the annular pattern 22 of approximately 12 μm or less, butis almost unobservable beyond 12 μm.

It is to be noted that the inner diameter of the annulus ring of theannular pattern 22 fell within a range from 4.14 μm to 48.25 μm in theaforementioned embodiment, wherein it is also allowable to appropriatelyselect an optimum range case-by-case, because every light exposureapparatus has a different influential range of the flare. Smallersetting of the width of the annulus ring, which was set to 2.76 μm inthe aforementioned embodiment, will make it possible to further finelyquantify the influence of the local flare corresponding to the distance.

Local flare intensity distribution of a point light source is nowassumed by a double-Gaussian distribution expressed as below:

$\begin{matrix}{{f(r)} = {A\left\{ {{\frac{1}{\sigma_{1}^{2}}{\exp\left( {- \frac{r^{2}}{2\sigma_{1}^{2}}} \right)}} + {\frac{B}{\sigma_{2}^{2}}{\exp\left( {- \frac{r^{2}}{2\sigma_{2}^{2}}} \right)}}} \right\}}} & (1)\end{matrix}$

-   -   r: distance of flare;    -   A: constant;    -   σ₁, σ₂: standard deviation in Gaussian distribution; and    -   B: intensity ratio in Gaussian distribution.

Local flare energy of the individual test patterns shown in FIGS. 3A to3C can be determined by integrating equation (1) using a point imageintensity distribution calculation unit 1. FIG. 6 shows a fitted resultof the results shown in FIG. 5 through integration using equation (1).The fitted result is satisfactory as shown in the drawing, and thisproves an excellent accuracy in the calculation of flare intensitydistribution. The flare energy corresponding to the individual patternscan be determined by calculating the flare energy from opening portionsin the periphery of the pattern, using equation (1).

(2) Step S2

First, an integrated value of equation (1) is obtained using a photomaskhaving a transmissive portion over the entire surface thereof. Thisvalue is normalized as 100%, and is defined as an effective numericalaperture.

Relation between the effective numerical aperture and dimensionalvariation can be determined by using a photomask-for-testing 25, shownin FIG. 7A, having a measurement pattern 23 and a dummy pattern 24arranged therearound. FIG. 7B shows an enlarged view of the measurementpattern 23. Dimensional variation of the measurement pattern 23 undervaried dimension of the dummy pattern 24 on a halftone-type phase shiftmask is then calculated in relation to the effective numerical aperture,using a flare energy-dimensional variation calculation unit 2 andvarious photomasks-for-testing 25 differing in area of the dummy pattern24. Results of the calculation is shown in FIG. 8. It is found that theeffective numerical aperture and the dimensional variation is almost ina linear relation. The dimensional variation for the unit numericalaperture herein is found to be 0.23 nm.

(3) Step S3

In the practical local flare correction of the photomask, it isnecessary to handle the dimensional variation of the pattern inconsideration of so-called MEEF (mask error enhancement factor) whichexpresses dimensional variation of the resist pattern. Correction amountM per unit numerical aperture can be determined by the equation below:

M=dimensional variation per unit numerical aperture of the individualpattern/MEEF.

Using the flare energy-dimensional correction amount calculation unit 3and the equation in the above, a relation between the flare energy anddimensional variation determined in step S2 is converted into a relationbetween the flare energy and mask dimensional correction amount. Anexperimentally-obtained value of MEEF is 1.5, so that the maskcorrection amount per unit numerical aperture of the individual patternsis given as 0.17 nm.

(4) Step S4

FIG. 9 is a schematic drawing showing a design data in a single shotregion of the photomask, and FIG. 10 is a schematic drawing showing anexposure layout of a plurality of shot regions. In FIG. 9, a rectangularregion surrounded by a solid line expresses mask data corresponding to asingle shot region 31, and rectangular regions surrounded by a brokenline express flare regions 32 in which the flare around the centerpoints thereof should be considered. FIG. 10 shows an exposure layout ofthe shot regions in light exposure on a wafer 33, which is a targetobject for pattern transfer, wherein every single rectangle surroundedby solid lines expresses a single shot region 31. The hatched shotregions 31 are effective shot regions.

For calculation of the effective numerical aperture of the flare region32 surrounded by the broken line around point A in FIG. 9, it is allenough to consider only the shot region 31 because the entire portion ofthe flare region 32 falls in the shot region 31. In contrast to this,for calculation of the effective numerical aperture of the flare region32 surrounded by the broken line around point B, the mask pattern datafor the shot region 31 only is insufficient because a part of the flareregion 32 falls outside the shot region 31. In this embodiment, usingthe numerical aperture calculation unit 4, the effective numericalaperture is calculated taking not only the shot region 31, but also theexposure layout of a plurality of shot regions 31 shown in FIG. 10 intoconsideration, in other words, while considering also flare from aplurality of (three in the illustrated example) shot regions 31 locatedaround a target shot region as shown in FIG. 11.

In view of raising the process speed, the calculation herein adoptsso-called area density method, by which the shot region 31 is dividedinto a plurality of correction regions, and the numerical aperture iscalculated for every correction region. More specifically, the shotregion 31 is divided according to a several-micrometer-square meshwithin a range typically 100 μm away from the target pattern in theexposure region, which is 1-μm-square mesh for example, and thenumerical aperture is calculated assuming it as uniform within the mesh.This technique, called area density method, is successful in raising theprocessing speed to a considerable degree.

(5) Step S5

Thereafter, using the dimension calculation unit 5, the values of theeffective numerical aperture of the individual patterns calculated instep S4 are entered to the equation, obtained in step S3, expressingrelation between the numerical aperture and mask dimensional correctionamount, so as to calculate values of the dimensional correction amountof the mask pattern having the individual patterns, to thereby correctthe mask pattern data of the photomask.

As has been described in the above, the present embodiment makes itpossible to estimate and correct flare with an extremely high accuracy,over the entire portion of a single shot region, to realize alithographic process causative of only an extremely small dimensionalvariation in line width, and further to thereby realize highly-reliablesemiconductor devices.

Modified Example

Next paragraphs will explain modified example 1 of the first embodiment.The present modified example is different from the first embodiment inthat an average numerical aperture ascribable to a plurality of shotregions is used in place of the mask pattern data for other shot regionsother than the target shot region for the calculation.

FIG. 12 is a block diagram showing a schematic configuration of a maskpattern data correction device of modified example 1.

The data correction device is configured as having a point imageintensity distribution calculation unit 1 calculating flare intensitydistribution (point image intensity distribution) based on a result ofdimensional measurement of a test pattern using a predeterminedphotomask-for-testing; a flare energy-dimensional variation calculationunit 2 calculating a relation between flare energy (effective numericalaperture) and dimensional variation using a dummy photomask adjusted inthe numerical aperture; a flare energy-dimensional correction amountcalculation unit 3 calculating a relation between flare energy anddimensional correction amount; a numerical aperture calculation unit 6calculating, for every single shot region, flare energy for a maskpattern corresponding to a transferred pattern, while considering anaverage numerical aperture ascribable to a plurality of shot regions;and a dimension calculation unit 5 calculating a dimension of the maskpattern necessary for obtaining the transferred pattern of apredetermined dimension, using the flare energy calculated by thenumerical aperture calculation unit 6.

FIG. 13 is a flow chart step-wisely showing the correction method usingthe above-described data correction device.

First, steps S1, S2 and S3 in FIG. 2 explained in the first embodimentare executed.

Next in step S1, using a numerical aperture calculation unit 6, theeffective numerical aperture in the shot region 31 is calculated whileconsidering an average numerical aperture ascribable to a plurality ofshot regions. In this process, the effective numerical aperture in theshot region 31 is corrected using data of a photomask 43, shown in FIG.14, having a mask pattern 41 and a dummy pattern 42 arranged therearoundand thereby having an adjusted numerical aperture. The area densitymethod is adopted herein in view of raising the process speed.

Thereafter in step S5, using the dimension calculation unit 5, thevalues of the effective numerical aperture of the individual patternscalculated in step S11 are entered to the equation, determined in stepS3, expressing relation between the numerical aperture and maskdimensional correction amount, so as to calculate values of thedimensional correction amount of the mask pattern having the individualpatterns, to thereby correct the mask pattern data of the photomask.

As has been described in the above, the present modified example makesit possible to estimate and correct flare with an extremely highaccuracy and in a simple manner, over the entire portion of a singletarget shot region, by considering influence of flare from theperipherals of the target shot region as an average numerical aperture,and also makes it possible to realize a lithographic process causativeof only an extremely small dimensional variation in line width, andfurther to thereby realize highly-reliable semiconductor devices.

Modified Example 2

Next paragraphs will describe modified example 2 of the firstembodiment.

The present modified example uses not only the mask pattern data ofother shot regions other than the target shot region for thecalculation, but uses also the mask pattern data of the chip regionsother than the target chip region for the calculation.

Correction processing of design data, such as flare correction,proximity effect correction and so forth, is generally carried outrespectively for every device chip region. FIG. 15A schematically showsa single shot region of an actual device, and FIG. 15B shows an enlargedview of a single chip region shown in FIG. 15A. The shot region 31 has4×6 chip regions 111 arranged therein. A pattern of point “A” iscorrected in the mask dimension thereof, by calculating flare energyfrom the flare region 32, which is a range (surrounded by a broken line)possibly be affected by the surrounding regions. Also a pattern of point“B” may similarly be affected by the flare region 32 indicated as beingsurrounded by a broken line, but the conventional technique does notconsider the influence of the surrounding chip regions, becausecalculation of the flare energy is made on the chip basis. In the lightexposure, it is also necessary for the conventional technique to takeinfluences of the surrounding shots into consideration, because thelight exposure is carried out based on an exposure layout shown in FIG.10.

In the present modified example, it is allowable, using the datacorrection device explained in the first embodiment, to execute steps S1to S3 and step S5 similarly to as described in the above, and tocalculate, in step S4, the flare energy of the individual mask patterns,wherein the effective numerical aperture is calculated for every chipregion, referring respectively to the pattern data of the chip regionadjacent to the target chip region, and pattern data of the shot regionadjacent to the target chip region inconsideration of the exposurelayout shown in FIG. 10.

It is also allowable to apply the present modified example to modifiedexample 1, and to calculate, in step S1, the flare energy of theindividual mask patterns, wherein the effective numerical aperture iscalculated for every chip region, referring respectively to the patterndata of the chip region adjacent to the target chip region, and patterndata of the shot region adjacent to the target chip regioninconsideration of the exposure layout shown in FIG. 10.

As has been described in the above, the present modified example makesit possible to estimate and correct flare with an extremely highaccuracy and in a simple manner, over the entire portion of a singlechip region, by considering influence of flare from the peripherals ofthe chip region as an average numerical aperture, and also makes itpossible to realize a lithographic process causative of only anextremely small dimensional variation in line width, and further tothereby realize highly-reliable semiconductor devices.

Second Embodiment

The present embodiment will explain light exposure correction adapted tothe long-range flare.

FIG. 16 is a block diagram showing a schematic configuration of a lightexposure correction device of the second embodiment.

The light exposure correction device is configured as having a pointimage intensity distribution calculation unit 1 calculating flareintensity distribution (point image intensity distribution) based on aresult of dimensional measurement of a test pattern using apredetermined photomask-for-testing; a flare energy-dimensionalvariation calculation unit 2 calculating a relation between flare energy(effective numerical aperture) and dimensional variation using a dummyphotomask adjusted in the numerical aperture; a dimensionalvariation-exposure energy calculation unit 7 calculating a relationbetween the dimensional variation and irradiation energy (exposureenergy) distribution; a numerical aperture calculation unit 4calculating, for every single shot region, flare energy for a maskpattern corresponding to a transferred pattern, based on an exposurelayout of a plurality of shot regions, or more specifically, whileconsidering flare from a plurality of shot regions located around everysingle shot region; a flare energy-exposure energy calculation unit 8calculating a relation between the flare energy and an irradiationenergy distribution; and an irradiation energy distribution adjustmentunit 9 adjusting the irradiation energy distribution of the exposurelight in the shot region based on the irradiation energy distributioncalculated in the above. The dimensional variation-exposure energycalculation unit 7 and the flare energy-exposure energy calculation unit8 herein composes an irradiation energy distribution calculation unitcalculating an irradiation energy distribution of the exposure light inthe shot region necessary for obtaining a transferred pattern of apredetermined dimension, using the flare energy calculated in the above.

FIG. 17 is a flow chart step-wisely showing the correction method usingthe above-described light exposure correction device.

First, steps S1 and S2 in FIG. 2 explained in the first embodiment areexecuted.

Next in step S12, using the dimensional variation-exposure energycalculation unit 7, a relation between dimensional variation andirradiation energy (exposure energy) distribution is determined. Therelation between the irradiation energy distribution and dimensionalvariation can be determined by measuring dimension of the transferredpatterns formed under light exposure varied in the exposure energy.

Next, step S4 in FIG. 2, explained in the first embodiment is executed.Next in step S13, using the flare energy-exposure energy calculationunit 8, a relation between the flare energy and irradiation energydistribution is determined, based on the relation between flare energyand dimensional variation determined in step S2, and also on therelation between irradiation energy distribution and dimensionalvariation determined in step S3.

Thereafter in step S14, using the irradiation energy distributioncalculation unit 9, values of the effective numerical aperture of theindividual patterns, calculated in step S4, are converted into anirradiation energy distribution, and an irradiation energy distributionto be corrected is determined, using the relation between the flareenergy and irradiation energy distribution determined in step S13.

As has been described in the above, the present embodiment makes itpossible to estimate and correct flare with an extremely high accuracy,over the entire portion of a single shot region, to realize alithographic process causative of only an extremely small dimensionalvariation in line width, and further to thereby realize highly-reliablesemiconductor devices.

Modified Example

Next paragraphs will describe a modified example of the secondembodiment. This embodiment differs from the first embodiment in that anaverage numerical aperture of a plurality of shot regions is used, inplace of the mask pattern data of other shot regions other than thetarget shot region for the calculation.

FIG. 18 is a block diagram showing a schematic configuration of a maskpattern data correction device according to the present modifiedexample.

The data correction device is configured as having a point imageintensity distribution calculation unit 1 calculating flare intensitydistribution (point image intensity distribution) based on a result ofdimensional measurement of a test pattern using a predeterminedphotomask-for-testing; a flare energy-dimensional variation calculationunit 2 calculating a relation between flare energy (effective numericalaperture) and dimensional variation using a dummy photomask adjusted inthe numerical aperture; a dimensional variation-exposure energycalculation unit 7 calculating a relation between the dimensionalvariation and irradiation energy (exposure energy) distribution; anumerical aperture calculation unit 6 calculating, for every single shotregion, flare energy for a mask pattern corresponding to a transferredpattern, while considering an average numerical aperture ascribable to aplurality of shot regions; a flare energy-exposure energy calculationunit 8 calculating a relation between the flare energy and anirradiation energy distribution; and an irradiation energy distributionadjustment unit 9 adjusting the irradiation energy distribution of theexposure light in the shot region based on the irradiation energydistribution calculated in the above.

FIG. 19 is a flow chart step-wisely showing the correction method usingthe above-described light exposure correction device.

First, steps S1 and S2 in FIG. 17 explained in the first embodiment areexecuted.

Next in step S11, using a numerical aperture calculation unit 6, theeffective numerical aperture in the shot region 31 is calculated whileconsidering an average numerical aperture ascribable to a plurality ofshot regions. In this process, the effective numerical aperture in theshot region 31 is corrected using data of a photomask 43, shown in FIG.14, having a mask pattern 41 and a dummy pattern 42 arranged therearoundand thereby having an adjusted numerical aperture. The area densitymethod is adopted herein in view of raising the process speed.

Next, step S13 in FIG. 17 explained in the second embodiment isexecuted.

Thereafter in step S14, using the irradiation energy distributioncalculation unit 9, values of the effective numerical aperture of theindividual patterns, calculated in step S11, are converted into anirradiation energy distribution, and an irradiation energy distributionto be corrected is determined using the relation between the flareenergy and irradiation energy distribution determined in step S13.

As has been described in the above, the present modified example makesit possible to estimate and correct flare with an extremely highaccuracy and in a simple manner, over the entire portion of a singletarget shot region, by considering influence of flare from theperipherals of the target shot region as an average numerical aperture,and also makes it possible to realize a lithographic process causativeof only an extremely small dimensional variation in line width, andfurther to thereby realize highly-reliable semiconductor devices.

It is also allowable to apply the technical spirit of the modifiedexample of the first embodiment to the second embodiment and themodified example thereof, and to calculate, in step S4 (step S11 in themodified example), the flare energy of the individual mask patterns,wherein the effective numerical aperture is calculated for every chipregion, referring respectively to the pattern data of the chip regionadjacent to the target chip region, and pattern data of the shot regionadjacent to the target chip region in consideration of the exposurelayout shown in FIG. 10.

Third Embodiment

The present embodiment will explain light exposure correction adapted tothe long-range flare.

The long-range flare exerts its influence over a range as long asseveral millimeters, and shows a moderate variation in the intensitydistribution thereof rather than in a local manner. FIG. 20 shows ageneral light exposure apparatus. In the light exposure apparatus, lightL from an unillustrated light source is narrowed through a shutter 101,and is allowed to pass through an optical lens 102, and thereby reachesa photoresist on the surface of a wafer. A part of the light L hereinreaches a portion 103 outside the target shot region 4, which isrecognized as flare. In the present embodiment, the flare is measuredusing an illuminance sensor mounted on the light exposure apparatus.

FIG. 21 is a block diagram showing a schematic configuration of a lightexposure correction device according to the third embodiment.

The light exposure correction device is configured as having anilluminance sensor 51 which is a flare energy measurement unitmeasuring, when the shot region is irradiated by the exposure light,flare energy generated around the shot region; an irradiation energydistribution calculation unit 52 calculating irradiation energydistribution of the exposure light in the shot region necessary forobtaining the transferred pattern of a predetermined dimension, based onthe measured flare energy; and an irradiation energy distributionadjustment unit 53 adjusting irradiation energy distribution of theexposure light in the shot region, based on the calculated irradiationenergy distribution.

FIG. 22 is a flow chart step-wisely showing a correction method usingthe above-described light exposure correction device.

The method of correcting light exposure of the present embodimentcomprises three steps described below:

(1) measurement of flare energy generated around the shot region (stepS21);

(2) calculation of an irradiation energy distribution of the exposurelight in the shot region (step S22); and

(3) adjustment of the irradiation energy distribution of the exposurelight in the shot region (step S23).

The following paragraphs will detail the individual steps.

(1) Step S21

First, flare energy generated around the shot region is measured usingthe illuminance sensor.

FIG. 23A and FIG. 23B shows measurement of flare irradiated outside atarget shot region, wherein FIG. 23A is a schematic drawing of the shotregion which is a site of measurement of the flare, and FIG. 23B is acharacteristic chart showing results of the measurement.

In FIG. 23B, the abscissa plots distance from the peripheral portion ofthe shot region, and the ordinate plots flare energy (%). Irradiatedenergy obtained through a portion allowing complete transmission of thelight in the shot region is normalized by 1, and irradiated energyoutside the shot region is defined as flare energy. FIG. 23B shows onlyresults of a linear measurement, wherein it is also allowable to measurethe flare over the entire region outside the shot region.

(2) Step S22

An effective energy distribution in the target shot region can bedetermined by summing up flare from the adjacent shot regions typicallyin the exposure layout including a plurality of shot regions as shown inFIG. 10, using the irradiation energy distribution calculation unit 52.

(3) Step S23

The exposure energy distribution is adjusted, using the irradiationenergy distribution adjustment unit 53, so as to make the calculatedeffective energy distribution uniform.

As has been described in the above, the present embodiment makes itpossible to estimate and correct flare with an extremely high accuracy,over the entire portion of a single shot region, to realize alithographic process causative of only an extremely small dimensionalvariation in line width, and further to thereby realize highly-reliablesemiconductor devices.

Other Embodiments Applied with the Present Invention

The individual units for composing the data correction device and lightexposure correction device, and the individual steps (steps S1 to S5 inFIG. 2; steps S1 to S3, S11 and S5 in FIG. 13; steps S1, S2, S12, S4,S13 and S14 in FIG. 17; steps S1, S2, S12, S11, S13 and S14 in FIG. 19;steps S21 to S23 in FIG. 22, etc.) according to the above-describedembodiments can be realized by running a program stored in a RAM, ROMand so forth of a computer. Any programs and any computer-readablerecording medium having the program stored therein are also included ina scope of the present invention.

More specifically, the above-described program is provided to acomputer, typically as being recorded in a recording medium such asCD-ROM, or as being mediated by various transmission media. Examples ofthe recording medium storing the program, other than CD-ROM, includeflexible disk, hard disk, magnetic tape, magneto-optical disk andnon-volatile memory card. On the other hand, what is available as theprogram transmission media is a communication medium (wired linetypically using optical fiber or the like, and wireless line, etc.) in acomputer network (LAN, WAN such as the Internet, wireless communicationnetwork, etc.) allowing a program information to transmit on a carrierwave for the supply.

The program is also included in a scope of the present invention notonly for the case where the functions of the aforementioned embodimentsare realized through execution of a supplied program, but also for thecase where the functions of the aforementioned embodiments are realizedby the program in cooperation with an OS (operating system) or with anyother application software or the like, run on the computer, and stillalso for the case where the functions of the aforementioned embodimentsare realized by the entire portion or a part of processes of thesupplied program executed by a function expansion board or a functionexpansion unit of the computer.

As one example, FIG. 24 shows a schematic drawing of an internalconfiguration of a personal user terminal device. In the drawing,reference numeral 1200 denotes a computer PC. The PC 1200 has a CPU1201, executes a device control software stored in a ROM 1202 or in ahard disk (HD) 1211, or supplied from a flexible disk drive (FD) 1212,to thereby generally control the individual devices connected to asystem bus.

1. A method of correcting a mask pattern used in pattern transfer, ontoa target object having a plurality of target regions for patterntransfer, of a photomask under light exposure repeated multiple numberof times to thereby form a transferred pattern, comprising: calculating,for every single one of shot regions having a transferred pattern formedby a single time of light exposure through a mask pattern and everysingle one of a plurality of chip regions comprised in one of said shotregions, a numerical aperture of said mask pattern corresponding to saidtransferred pattern onto said target object based on an exposure layoutof the plurality of shot regions while considering a first flare due toinfluence from the peripherals of said shot region and a second flaredue to influence from the peripherals of said chip region; andcalculating a dimension of said mask pattern necessary for obtainingsaid transferred pattern of a predetermined dimension, using saidnumerical aperture calculated in the above; wherein said calculatingsaid numerical aperture calculates an average numerical aperture for aplurality of said shot regions and chip regions, corrects a design valueof said numerical aperture for said shot regions and chip regions forthe calculation using said average numerical aperture, and calculates aneffective value of said numerical aperture for said shot regions andchip regions for the calculation.